Publications

Hydrogen has received increased attention in the last decades as a green energy carrier and a promising future fuel. The integration of hydrogen as well as the development of cogeneration plants makes the energy sector more eco-friendly and sustainable. The aim of this paper is the investigation of a solar-fed cogeneration system that can produce power and compressed green hydrogen. The examined unit contains a parabolic trough collector solar field a thermal energy storage tank an organic Rankine cycle and a proton exchange membrane water electrolyzer. The installation also includes a hydrogen storage tank and a hydrogen compressor. The unit is analyzed parametrically in terms of thermodynamic performance and economic viability in steady-state conditions with a developed and accurate model. Taking into account the final results the overall energy efficiency is calculated at 14.03% the exergy efficiency at 14.94% and the hydrogen production rate at 0.205 kg/h. Finally the payback period and the net present value are determined at 9 years and 122 k€ respectively.

The world is rapidly adopting renewable energy alternatives at a remarkable rate to address the ever-increasing environmental crisis of CO2 emissions. Renewable Energy Systems (RES) offers enormous potential to decarbonize the environment because they produce no greenhouse gases or other polluting emissions. However the RES relies on natural resources for energy generation such as sunlight wind water geothermal which are generally unpredictable and reliant on weather season and year. To account for these intermittencies renewable energy can be stored using various techniques and then used in a consistent and controlled manner as needed. Several researchers from around the world have made substantial contributions over the last century to developing novel methods of energy storage that are efficient enough to meet increasing energy demand and technological break-throughs. This review attempts to provide a critical review of the advancements in the Energy Storage System (ESS) from 1850–2022 including its evolution classification operating principles and comparison

Recently the management of water and wastewater is gaining attention worldwide as a way of conserving the natural resources on the planet. The traditional wastewater treatment in Oman is such that the treated effluent produced is only reused for unfeasible purposes such as landscape irrigation cooling or disposed of in the sea. Introducing more progressive reuse applications can result in achieving a circular economy by considering treated effluent as a source of producing new products. Accordingly wastewater treatment plants can provide feedstock for green hydrogen production processes. The involvement of the wastewater industry in the green pathway of production scores major points in achieving decarbonization. In this paper the technical and economic feasibility of green hydrogen production in Oman was carried out using a new technique that would help explore the benefits of the treated effluent from wastewater treatment in Oman. The feasibility study was conducted using the Al Ansab sewage treatment plant in the governate of Muscat in Wilayat (region) Bousher. The results have shown that the revenue from Al Ansab STP in a conventional case is 7.02 million OMR/year while sustainable alternatives to produce hydrogen from the Proton Exchange Membrane (PEM) electrolyzer system for two cases with capacities of 1500 kg H2/day and 50000 kg H2/day would produce revenue of 8.30 million OMR/year and 49.73 million OMR/year respectively.

In this episode titled "The Commission's support to the hydrogen ecosystem" our CEO Jorgo Chatzimarkakis discusses with Rosalinde van der Vlies Clean Planet Director DG RTD - European Commission. Starting off on how Rosalinde joined the Commission the two speakers discuss the Commission's support in developing a hydrogen ecosystem also in light of its participation in the Clean Hydrogen Partnership and the implications arising from the REPowerEU.

This paper looks at the possible role of ‘green gas’ in the decarbonisation of heat in the United Kingdom.  The option is under active discussion at the moment because of the UK’s rigorous carbon reduction targets and the growing realisation that there are problems with the ‘default’ option of electrifying heat. Green gas appears to be technically and economically feasible.  However as the paper discusses there are major practical and policy obstacles which make it unlikely that the government will commit itself to developing ‘green gas’ in the foreseeable future.

This paper examines the prospect of PEM (Proton Exchange Membrane) electrolyzers and fuel cells to partake in European electrical ancillary services markets. First the current framework of ancillary services is reviewed and discussed emphasizing the ongoing European harmonization plans for future frequency balancing markets. Next the technical characteristics of PEM hydrogen technologies and their potential uses within the electrical power system are discussed to evaluate their adequacy to the requirements of ancillary services markets. Last a case study based on a realistic representation of the transmission grid in the north of the Netherlands for the year 2030 is presented. The main goal of this case study is to ascertain the effectiveness of PEM electrolyzers and fuel cells for the provision of primary frequency reserves. Dynamic generic models suitable for grid simulations are developed for both technologies including the required controllers to enable participation in ancillary services markets. The obtained results show that PEM hydrogen technologies can improve the frequency response when compared to the procurement with synchronous generators of the same reserve value. Moreover the fast dynamics of PEM electrolyzers and fuel cells can help mitigate the negative effects attributed to the reduction of inertia in the system.

The large-amplitude sloshing behavior of liquid hydrogen in a tank for heavy-duty trucks may have adverse effects on the safety and stability of driving. With successful application of liquid hydrogen in the field of new energy vehicles the coupled thermodynamic performance during liquid hydrogen large-amplitude sloshing becomes more attractive. In this paper a three-dimensional numerical model is established to simulate the thermodynamic coupling characteristics during liquid hydrogen sloshing in a horizontal tank for heavy-duty trucks. The calculation results obtained by the developed model are in good agreement with experimental data for liquid hydrogen. Based on the established 3D model the large-amplitude sloshing behavior of liquid hydrogen under extreme acceleration as well as the effects of acceleration magnitude and duration on liquid hydrogen sloshing is numerically determined. The simulation results show that under the influence of liquid hydrogen large-amplitude sloshing the convective heat transfer of fluid in the tank is greatly strengthened resulting in a decrease in the vapor temperature and an increase in the liquid temperature. In particular the vapor condensation caused by the sloshing promotes a rapid reduction of pressure in the tank. When the acceleration magnitude is 5 g with a duration of 200 ms the maximum reduction of ullage pressure is 1550 Pa and the maximum growth of the force on the right wall is 3.89 kN. Moreover the acceleration magnitude and duration have a remarkable influence on liquid hydrogen sloshing. With the increase in acceleration magnitude or duration there is a larger sloshing amplitude for the liquid hydrogen. When the duration of acceleration is 200 ms compared with the situation at the acceleration magnitude of 5 g the maximum reductions of ullage pressure decrease by 9.46% and 55.02% and the maximum growth of forces on the right wall decrease by 80.57% and 99.53% respectively at 2 g and 0.5 g. Additionally when the acceleration magnitude is 5 g in contrast with the situation at a duration of acceleration of 200 ms the maximum-ullage-pressure drops decrease by 8.17% and 21.62% and the maximum increase in forces on the right wall decrease by 71.80% and 88.63% at 100 ms and 50 ms respectively. These results can provide a reference to the safety design of horizontal liquid hydrogen tanks for heavy-duty trucks.

The emerging energy transition is particularly described as a move towards a cleaner lower-carbon system. In the context of the global shift towards sustainable energy sources this paper reviews the potential and roadmap for hydrogen energy as a crucial component of the clean energy landscape. The primary objective is to present a comprehensive literature overview illuminating key themes trends and research gaps in the scientific discourse concerning hydrogen production and energy policy. This review focuses particularly on specified geographic contexts with an emphasis on understanding the unique energy policies related to renewable energy in Brazil Austria and Germany. Given their distinct social systems and developmental stages this paper aims to delineate the nuanced approaches these countries adopt in their pursuit of renewable energy and the integration of hydrogen within their energy frameworks. Brazil exhibits vast renewable energy potential particularly in wind and solar energy sectors positioning itself for substantial growth in the coming years. Germany showcases a regulatory framework that promotes innovation and technological expansion reflecting its highly developed social system and commitment to transitioning away from fossil fuels. Austria demonstrates dedication to decarbonization particularly through the exploration of biomethane for residential heating and cooling.

Alongside the rapid expansion of wind power installation in China wind curtailment is also mounting rapidly due to China’s energy endowment imbalance. The hydrogen-based wind-energy storage system becomes an alternative to solve the puzzle of wind power surplus. This article introduced China’s energy storage industry development and summarized the advantages of hydrogen-based wind-energy storage systems. From the perspective of resource conservation it estimated the environmental benefits of hydrogen-based wind-energy storages. This research also builds a valuation model based on the Real Options Theory to capture the distinctive flexible charging and discharging features of the hydrogen-based wind-energy storage systems. Based on the model simulation results including the investment value and operation decision of the hydrogen energy storage system with different electricity prices system parameters and different levels of subsidies are presented. The results show that the hydrogen storage system fed with the surplus wind power can annually save approximately 2.19–3.29 million tons of standard coal consumption. It will reduce 3.31–4.97 million tons of CO2 SO2 NOx and PM saving as much as 286.6–429.8 million yuan of environmental cost annually on average. The hydrogen-based wind-energy storage system’s value depends on the construction investment and operating costs and is also affected by the meanreverting nature and jumps or spikes in electricity prices. The market-oriented reform of China’s power sector is conducive to improve hydrogen-based wind-energy storage systems’ profitability. At present subsidies are still essential to reduce initial investment and attract enterprises to participate in hydrogen energy storage projects.

The demand for clean and sustainable energy solutions is escalating as the global population grows and economies develop. Fossil fuels which currently dominate the energy sector contribute to greenhouse gas emissions and environmental degradation. In response to these challenges hydrogen storage technologies have emerged as a promising avenue for achieving energy sustainability. This review provides an overview of recent advancements in hydrogen storage materials and technologies emphasizing the importance of efficient storage for maximizing hydrogen’s potential. The review highlights physical storage methods such as compressed hydrogen (reaching pressures of up to 70 MPa) and material-based approaches utilizing metal hydrides and carboncontaining substances. It also explores design considerations computational chemistry high-throughput screening and machine-learning techniques employed in developing efficient hydrogen storage materials. This comprehensive analysis showcases the potential of hydrogen storage in addressing energy demands reducing greenhouse gas emissions and driving clean energy innovation.